A wireless microphone (which may be referred as a radio microphone) is typically a microphone without a physical cable connecting the wireless microphone directly to associated sound recording or amplifying equipment. There are numerous standards spanning different transmission spectra and transmission technologies used to support a wireless microphone's connection to associated receiving equipment. For example, the connection may utilize ultra-high frequencies (UHF) or very high frequency (VHF) frequencies with an analog modulation technique such as frequency modulation (FM) or amplitude modulation (AM). Some low cost wireless models may use infrared light typically requiring a direct line of sight between the wireless microphone and the receiving apparatus, while costlier radio frequency models may use radio frequency signal that does not require a direct line of sight. Some models operate on a single fixed frequency, but the more advanced models often operate on a user selectable frequency to avoid interference allow the use of several wireless microphones at the same time.
Wireless microphones are often advantageous by providing greater freedom of movement for the artist or speaker, avoidance of cabling problems common with wired microphones, and reduction of cable “trip hazards” in the performance space. However, wireless microphones may have deficiencies resulting from limited range, excessive range causing interference to/from other radio equipment, and limited operating time. Operating time is limited relative to battery life and is typically shorter than a normal condenser microphone due to greater drain on batteries from transmitting circuitry from circuitry providing extra features.
Wireless microphone technology is currently moving from analog approaches such a FM to digital approaches. However, digital approaches often involve complex modulation (i.e., simultaneous amplitude and phase modulation of the transmitted carrier waveform). Such complex modulation often complicates the modulator as compared to analog approaches. For example, traditional FM systems are often highly optimized in terms of battery life (i.e., power consumption) and monetary cost.